Hi Martin, On Wed, 8 Jan 2014 21:54:20 +0100, Martin Herrman wrote: > my apologies if I bother you with simple noob questions in this mail. > On the other hand, if so they should be easy to answer :-) > > My mainboard is a Gigabyte GA-Z68MX-UD2H-B3 which has a iTE IT8728 and > core i5 2500T (sandy bridge). > > Unfortunately this board is not (yet :-)) on the list yet: > > http://lm-sensors.org/wiki/Configurations/Gigabyte > > So I'm trying to understand and optimize the output of sensors using a > file in /etc/sensors.d/ > > My questions: > 1. coretemp outputs 5 temperatures. The last 4 are the cores, but what > is the value of the first one? (my guess: the temperature of the > highest core) The first temperature reported by coretemp is the "CPU package temperature". I can't remember if it's a separate sensor or just computed by the hardware as the maximum of the core temperatures. > 2. coretemp temperatures have (according to sensors -u) a _max, _crit > and _crit_alarm. How are these values determined? Does lm_sensors have > a database of existing cpu's and their max temperature specifications? On recent Intel processors these values are read from the CPU itself. On older processors the driver has heuristics to figure them out. It may get them wrong in a few cases. Check the driver documentation for a list of known limits for older processors. http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/hwmon/coretemp With a Core i5 you should be on the safe side. > 3. (follow-up on Q2) what is the difference between _max and _crit? > What happens when each of them is reached? What is the role of > _crit_alarm and how will the alarm be noticed? For the coretemp driver, _max is the temperature at which point all cooling options should be enabled at full throttle. _crit is the temperature at which the CPU integrity is no longer guaranteed. You don't want to reach that temperature, ever. _crit_alarm is raised when the measured (_input) temperature goes above the _crit limit. This is checked by polling as the coretemp driver currently doesn't have a notification mechanism. libsensors doesn't support such notifications anyway. This should be added but I don't have the time for that. > 4. (follow-up on Q3) how can I change the values for _max and _crit? I > tried 'set temp1_max 60' but that doesn't work. (sensors -s complains) These are read-only limits specific to your CPU model. You don't get to change them, sorry. > 5. what is the difference between fan1_alarm and fan1_beep? fan1_alarm triggers when fan1_input goes below fan1_min. It is read-only. fan1_beep is writable and tells whether the alarm triggering will result in your system beeping or not. Note that your board must be properly wired (i.e. beep output of the monitoring chip routed to the on-board buzzer or PC speaker) for this to work, which is unfortunately not always the case. > 6. (follow-up on Q5) how do I set fan1_alarm? set fan1_alarm 1 doesn't > work. (sensors -s complains) You don't, this is a read-only value which gets set by the hardware by comparing fan1_input with fan1_min. It is set and cleared by the hardware. What were you trying to achieve by setting it to 1 manually? > 7. it8728 reports 3 different temps. When CPU is at full load, one of > them increases, but the value is much lower than the one reported by > coretemp (about 10 degrees lower). sensors outputs that it is Intel > PECI. According to the explanation on Wikipedia > (http://en.wikipedia.org/wiki/Platform_Environment_Control_Interface) > the temperature should be negative and increase towards 0 when cpu > temperature rises. Why does sensors show different values? PECI is the low level specification. Users wouldn't understand that sensors returns negative, relative temperature values. So all drivers supporting PECI compute the actual temperature based on the negative PECI value and the base temperature (maximum temperature supported by the component being monitored, the CPU in this case.) For some drivers (such as it87) this is even done by the hardware itself. This assumes that the base temperature is known and correct, which is unfortunately not always the case. In the case of the IT8728F chip, the base temperature should be set by the BIOS depending on your CPU model. The fact that the values differ between coretemp and it87 suggests that the BIOS and the coretemp driver disagree about the base temperature (which matches temp1_crit for the coretemp driver.) > 8. it8728 shows another two temps. Likely one case temp and the other > one the south bridge? How can I find out? Check what the BIOS says, it typically shows two temperatures so that should tell you what temp2 is. Check if the motherboard documentation mentions anything. Then experiment by yourself (see what makes each temperature rise the most.) It is possible that the 3rd temperature is just noise. > 9. (from FAQ) "Do you have a database of sensors.conf entries for > specific boards? > No. Good idea though. If you would like to set one up on your website > send us mail and we will set up a link to it." > Why hasn't this been setup yet? Some sort of a database is at the > wiki, but doesn't contain many boards. Is any help still appreciated? > Is it just a table of manufacturer, type, sensors.conf file? (and > maybe some user registrations and comments by registered users?) It has not been setup because nobody took the time and energy to do so. Yes, it's "only" a set of configuration files indexed by board manufacturer/model. But you need to store them somewhere in a safe way, provide a way to search and retrieve them, provide a way to add and amend them (with protection from spam or any form of abuse.) You are welcome to help, but no, this isn't a trivial task. > P.S. if answers can be found somewhere.. please let me know where to > find the documentation! Some parts of http://www.lm-sensors.org/wiki/Documentation are worth a read, but it did not contain an answer to all your questions above. -- Jean Delvare http://khali.linux-fr.org/wishlist.html _______________________________________________ lm-sensors mailing list lm-sensors@xxxxxxxxxxxxxx http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
